fix(#150): auto-register HEAD route for GET routes

src/http/core/response.ts

@@ -1262,59 +1262,64 @@
    *
    * @param body - Response body (string, Buffer, object, array, or undefined)
    */
   send(body?: string | Buffer | Record<string, unknown> | unknown[]): void {
     if (this.aborted) {
       return; // Silently ignore if connection aborted
     }
 
     if (this.finished) {
       return;
     }
 
     if (this.sending) {
       throw new Error('Response already being sent');
     }
 
     // Serialize body outside atomic so compression can inspect/modify headers
     let finalBody: string | Buffer | undefined;
 
     if (body === null || body === undefined) {
       finalBody = undefined;
     } else if (typeof body === 'string' || Buffer.isBuffer(body)) {
       finalBody = body;
     } else if (typeof body === 'object') {
       if (!this._headersSent && !this.hasHeader('content-type')) {
         this.setHeader('content-type', 'application/json; charset=utf-8');
       }
       finalBody = JSON.stringify(body);
     } else {
       finalBody = String(body);
     }
 
+    // RFC 9110 §9.3.2: HEAD responses must have identical headers to GET but no body.
+    if (this.req?.method === 'HEAD') {
+      finalBody = undefined;
+    }
+
     this.sending = true;
 
     // Apply compression if configured and body is present
     if (this.compressionHandler && this.req && finalBody) {
       const bodyBuffer = Buffer.isBuffer(finalBody) ? finalBody : Buffer.from(finalBody);
       this.compressionHandler
         .compressBuffer(this.req, this, bodyBuffer)
         .then((compressed) => this._sendInternal(compressed))
         .catch(() => {
           this.sending = false;
           if (this.finished || this.aborted || this._headersSent) {
             return;
           }
           // Drop headers the compression handler may have set so the
           // plaintext fallback isn't tagged with a Content-Encoding
           this.removeHeader('content-encoding');
           this.removeHeader('content-length');
           this.status(500);
           this._sendInternal('Internal Server Error');
         });
     } else {
       this._sendInternal(finalBody);
     }
   }
 
   /**
    * Internal method to perform the actual uWS send after optional compression

src/http/routing/route-registry.ts

@@ -245,6 +245,19 @@ export class RouteRegistry {
       metadata,
     });
 
+    // Auto-register HEAD route for GET routes (RFC 9110 §9.3.2)
+    if (normalizedMethod === 'GET') {
+      this.routes.set(`HEAD:${path}`, {
+        method: 'HEAD',
+        path,
+        uwsPath,
+        pattern,
+        paramNames,
+        isComplex,
+        handler,
+        metadata,
+      });
+    }
     // Get the uWS method function
     const uwsMethodFn = this.uwsApp[uwsMethod as keyof uWS.TemplatedApp] as any;